Registration project error in Xamarin forms - xamarin.forms

Question

I'm new here and a newbie in coding. I just tried this small project from YT. I copied everything and cannot figure out what is wrong with the error. ('x' is an undeclared prefix.)
Thanks in advance!
<Grid Margin="20,0,20,0" VerticalOptions="CenterAndExpand">
<Grid.RowDefinitions>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
</Grid.RowDefinitions>
<StackLayout Grid.Row ="0">
<Entry Placeholder ="UserName" FontSize ="16" x:Name =" EntryUserName"/>
</StackLayout>
<StackLayout Grid.Row="1">
<Entry Placeholder ="PassWord" IsPassword="true" FontSize ="16" x:Name =" EntryUserPassword"/>
</StackLayout>
<StackLayout Grid.Row="2">
<Entry Placeholder ="Email" FontSize ="16" x:Name =" EntryUserEmail"/>
</StackLayout>
<StackLayout Grid.Row="3">
<Entry Placeholder ="PhoneNumber" FontSize ="16" x:Name =" EntryUserPhoneNumber"/>
</StackLayout>
<StackLayout Grid.Row="4">
<Button Text="Register" HorizontalOptions="CenterAndExpand" WidthRequest="100" TextColor="White" BackgroundColor="Blue" Clicked="Handle_Clicked"/>
</StackLayout>
</Grid>
</StackLayout>

Answer 1

The Name attribute value of your Entry is prefixed with Space,which is not reasonable.
You can replace it with other valid characters.
For example:
replace
<StackLayout Grid.Row ="0">
<Entry Placeholder ="UserName" FontSize ="16" x:Name =" EntryUserName"/>
</StackLayout>
with:
<StackLayout Grid.Row ="0">
<Entry Placeholder ="UserName" FontSize ="16" x:Name ="mEntryUserName" />
</StackLayout>
Other entries are similarly named.
Please refer the following code:
<StackLayout>
<Grid Margin="20,0,20,0" VerticalOptions="CenterAndExpand" >
<Grid.RowDefinitions>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
<RowDefinition Height ="Auto"/>
</Grid.RowDefinitions>
<StackLayout Grid.Row ="0">
<Entry Placeholder ="UserName" FontSize ="16" x:Name ="mEntryUserName" />
</StackLayout>
<StackLayout Grid.Row="1">
<Entry Placeholder ="PassWord" IsPassword="true" FontSize ="16" x:Name ="mEntryUserPassword"/>
</StackLayout>
<StackLayout Grid.Row="2">
<Entry Placeholder ="Email" FontSize ="16" x:Name ="mEntryUserEmail"/>
</StackLayout>
<StackLayout Grid.Row="3">
<Entry Placeholder ="PhoneNumber" FontSize ="16" x:Name ="mEntryUserPhoneNumber"/>
</StackLayout>
<StackLayout Grid.Row="4">
<Button Text="Register" HorizontalOptions="CenterAndExpand" WidthRequest="100" TextColor="White" BackgroundColor="Blue" Clicked="Button_Clicked"/>
</StackLayout>
</Grid>
</StackLayout>
Then in YourPage.xaml.cs, you can access your entry in function Button_Clicked as follows:
private void Button_Clicked(object sender, EventArgs e)
{
System.Diagnostics.Debug.WriteLine("User Name is : " + mEntryUserName.Text +"<---> PassWord is = " + mEntryUserPassword.Text);
}